Plastics Breakthrough Allows for High-Durability Medical Devices

A new type of plastic could be used to create high-durability medical devices. When placed under shearing stress, this new plastic becomes stronger.

Almost every medical device contains one or more types of plastic. Plastic is inexpensive, malleable and lightweight. However, traditional plastics have often suffered from poor durability. For example, plastic-encapsulated smartphones can crack or chip when dropped from only a few feet. For medical devices, any cracks or chips in plastic-based products could prove lethal. However, that may change in the future.

According to researchers at Duke University, a new type of plastic could improve the durability of medical devices and other plastic-based products. When placed under shearing stress, the new plastic increases in strength.

The molecular structure of the new plastic gives it this unusual ability. Like most traditional plastics, this novel plastic has a carbon-based backbone. However, the individual carbon atoms in this plastic are arranged to form connected triangles. These carbon triangles extend in a long chain. Several bromine atoms are included in this structure. Researchers note that this arrangement of atoms can allow for constructive energy from destructive forces.

Most traditional polymer chains will fissure when exposed to shock or tugging forces. This can lead to structural failure. With this new plastic, shearing forces can break carbon-based triangles into a series of longer chains. This allows for bonding sites at the location of bromine atoms.

By including carboxylate molecules in the plastic, researchers were able to induce carboxylate bonding at bromine sites. With this addition, bromine-sited fissures create multiple cross-linked chains, increasing the strength of the plastic at damage sites. This novel plastic, known as a mechanophore, responds to mechanical forces instead of chemical exposure, heat or light.

To ensure that the novel plastic was able to make new bromine / carboxylate bonds consistently, researchers fed the plastic through a mechanical extruder. This extruder was used to force the new bromine / triangulated carbon plastic into a mold. Once this was done, the mechanophore plastic was transformed from pliable to extremely stiff. When nanoindentation was used to measure the plastic, researchers noted that the hardness of the material was 200 times greater than pre-extrusion.

The new plastic is able to “boost” its strength in a variety of mediums. Researchers noted that the plastic was even able to increase in strength when dissolved in a liquid solution. By disturbing the dissolved molecules, researchers were able to precipitate the cross-linking of bromine sites, creating a plastic gel that bonded with the sides of the solution container.

This new plastic could revolutionize the world of medical devices. With this mechanophore, implantable medical devices like stents, heart valves and joints could be designed with high-durability properties. Prosthetic limbs designed from the new mechanophore could also absorb stress, allowing for new uses.